Mysterious New Virus Found in Sick Dolphin

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In October 2010, the body of a young short-beaked common dolphin
was found stranded on a beach in San Diego, Calif. The sickly
female had lesions in its airway, and a necropsy showed that it
died of so-called tracheal bronchitis, likely due to an
infection.

Now, further investigation has revealed the dolphin's malaise was
caused by a virus that
scientists had never seen before, according to a new study.

The pathogen, which researchers propose should be named Dolphin
polyomavirus 1, or DPyV-1, is still quite mysterious. Scientists
say they don't know where it came from, how common it might be,
or what threat it poses to wildlife. [ Deep
Divers: Stunning Photos of Dolphins ]

"We don't even know if this is even a dolphin virus. It could
also represent a spillover event from another species," Simon
Anthony, a researcher who studies wildlife pathogens at Columbia
University, said in a statement. "It's no immediate cause for
alarm, but it's an important data point in understanding this
family of viruses and the diseases they cause."

Genetic analysis showed that the polyomavirus found in the San
Diego
dolphin was distinct from other known polyomaviruses (a
widespread family of small DNA viruses that can sometimes cause
infections and tumors in various animals). The pathogen appeared
to be most closely related to the California sea lion
polyomavirus, the researchers reported online on July 10 in the
journal
PLOS ONE.

"It's possible that many dolphins carry this virus or other
polyomaviruses without significant problems," said Judy St.
Leger, the director of pathology at SeaWorld in San Diego, who
performed the initial animal autopsy (or necropsy) on the
stranded dolphin.

"Or perhaps it's like the common cold, where they get sick for a
short while and recover," St. Leger added in a statement.

The researchers say they do not know of any other cases
resembling the stranded dolphin in San Diego, but they are
searching for more examples of polyomavirus in the species. The
team hopes to determine the prevalence of DPyV-1 in short-beaked
common dolphins and find out if it represents a significant
source of dolphin illness and mortality.

Understanding how viruses develop in marine mammals is important
for protecting endangered species, whose populations could
nosedive if they are hit by a deadly outbreak. And marine mammals
can
pick up pathogens that originated in other animals, even
humans.

Canine distemper virus, for example, has caused sickness in seals
and polar bears (often considered marine mammals since they spend
much of their time at sea). A strain of bird flu was blamed for a
mass die-off of New England harbor seals in 2011. Earlier this
year, researchers found that a group of
northern elephant seals off the coast of central California
was carrying the H1N1 virus strain, which caused a swine flu
outbreak in humans in 2009. The seals could have caught the
species-jumping pathogen from human feces dumped out of shipping
vessels or seabirds, the scientists speculated at the time.